Large-Eddy Simulation #181: TIBL (with restoring zones)

LES RUN #181: TIBL. We found that unrealistic east-west pressure-gradients were developing in our previous TIBL simulations with open boundary conditions. To correct for this in #181 we switched to periodic in both lateral directions and installed large "restoring zones" (900 m wide) in the east-west ends of the domain. This simulation is 800x120x69 grid-points with 15-m resolution in all directions and 0.5 s time-step was used. The western 6-km is over snow-covered land and the eastern 6-km over 279-K water. Click here to see the NMSTASK file .

The following image and animation is a horizontal slice of model output near the surface from the second half-hour of simulation. We are only showing the right half of the model domain (the part over water). To make the picture and animation, we have repeated the image once in the north-south direction to allow your eye to more easily track coherent structures across the domain and for a more direct comparison with the lidar PPI scans.

This numerical advection scheme used in this simulation is Sadourney (19??). It is used with the intention of preserving enstrophy, KE and vorticity, and therefore eliminate the non-physical downscale cascade of energy. The model relative humidity and passive tracer output has been used in a function to mimic the effects of aerosol swelling and increased lidar backscattering.

The following is a vertical east-west slice of model output for comparison with the lidar RHI-scans.

Here is an image of the pressure-perturbation fields of LES #149 (open E-W BCs) and #181 (periodic in lateral directions) for comparison.

Here is an image and an animation of the pressure-perturbation field on an east-west oriented vertical slice.

Here is an image and an animation of the model relative-humidity field on a horizontal slice near the surface.

Here is an image and an animation of the model relative-humidity field on a east-west vertical slice.

UW Lidar // Mar 16, 2000 //

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